1987 Fiscal Year Final Research Report Summary
Development of Method Evaluating Damaged places and Levels in Concrete Structures Through AE Monitoring
| Project/Area Number |
61850084
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| Research Category |
Grant-in-Aid for Developmental Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Field |
土木構造
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
SATAKE Masao Tohoku Niversity, Professor, 工学部, 教授 (50005188)
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| Co-Investigator(Kenkyū-buntansha) |
YAMANOUCHI Masaji Fukushima National Coollege of Technology, Associate Professor, 助教授 (80132570)
NIISEKI Shigeru Tohoku University,Research Associate, 工学部, 助手 (30005524)
TANO Hisataka Nihon University, Associate Professor, 工学部, 助教授 (00059700)
KISHINO Yuji Tohoku University, Associate Professor, 工学部, 助教授 (00005448)
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| Project Period (FY) |
1986 – 1987
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| Keywords | acoustic emission / concrete / fracturing level / deterioration / sea water / alkali-aggregate reaction / Kaiser effect / source location / wave form analysis / 凍結融解 |
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| Research Abstract |
The evaluation of hereditary stress through the kaiser effect was researched and the following results were clarified.
(1) The accuracy in evaluating the hereditary stress depends on the loading velocity of hereditary stress at each loading level which is determined on the basis of the ultimate strength of concrete specimens, but except for the almost fractured state, the influence of loading velocity on the accuracy in evaluating it is small and the mean error is ablut 4percent.
(2) The influence of mix proportion on the accuracy in evaluating the hereditary stress is small.
(3) The compressive and tensile stresses in alternately loaded plain concrete beams which are 15cm high, 15cm wide and 53cm long are evaluated through the cores cut out of them, and their errors are about 18 percent and 9.5 percent in average reespectively.
Defining the parameter m which expressed the increasing rate of logarithmic value of AE cumulative event count to unit inelastic axial strain, the damege levels of concrete specimens were evaluated and the following results were obtained.
(1) The m values have good correlation with the ultimate strength of concrete specimens and this relationship between them is approximately linear.
(2) The m values of concrete specimens damaged by the freezing and thawing action or repeated load are linearly correlated with various deterioration levels.
The AE method was applied to the early identification of alkali-aggregate reaction, and the following results were concluded.
(1) The maximum values of AE event rate in mortar specimens including reactive aggregate arise in 10 days and their values are extremely large in comparison with tghe ones composed of non-reactive aggregate.
(2) The increase of specimen length are linearly correlated with AE coumulative event count. In addition to the above, the accuracy of three-dimensional AE source location was improved.
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